A high fuel value coal-water slurry which can be injected directly into a furnace as a combustible fuel, can supplant large quantities of increasingly expensive fuel oil presently being used by utilities, factories, ships, and other commercial enterprises. Since the inert water vehicle reduces fuel value in terms of BTU/lb, it is desirable to minimize its concentration and maximize coal concentration for efficient use of the slurry as a fuel. High coal content also improves the combustion characteristics of the slurry.
It is important, therefore, that the slurry be loadable with finely divided coal in amounts as high, for example, as about 50% to 70% of the slurry. Despite such high solids loading, the slurry must be sufficiently fluid to be pumped and sprayed into the furnace. The coal particles must also be uniformly dispersed. The fluidity and dispersion must be stably maintained during storage.